NMEA 0183 over Ethernet, on Mar Azul

... written for Panbo by Ben Ellison and posted on Mar 9, 2010

Bob Ebaugh got some GX2100 installation help over on the Panbo forum, and that gave me a chance to bug him for some more information on the interesting system he's put together. Check it out above: two laptops connected wirelessly and simultaneously to MFD, AP, VHF/rxAIS, and Internet. Bob's a pilot and ex-networking engineer who didn't think he could write up the project well, but I think he did just fine...

My wife, Elaine, and I are in the process of a partial refit to Mar Azul, our DeFever 44 trawler. Mar Azul came to us with a 1st generation Furuno NavNet radar system integrated to a Simrad AP22 autopilot. While functional, we decided for various reasons to use a PC based solution, Coastal Explorer 2009, to meet our navigational requirements.

While that is pretty mundane by itself, what I think may interest Panbo readers is how we added a small Ethernet network to interface the navigation PC's at the upper and lower helms with the existing electronics. We used a Moxa RS422 to Ethernet server to connect the Coastal Explorer 2009 PC's to send and receive NMEA 0183 data to the other electronics. The PC's communicate with the Moxa server over Ethernet just as if the serial ports were hardwired to the PC's. I'm planning on using wireless WiFi, but I ran Ethernet cables as insurance in case I need them. Both PC's can simultaneously access the NMEA streams.

Moxa includes a Real Com port driver so that any PC application can see the NMEA data exactly like it was connected to an ordinary Com port on a PC. Coastal Explorer provides telnet access to a specific port, so we did not use or test this capability. But in theory, it should allow any PC program to access NMEA data over Ethernet even if the specific application does not support "telnet" access.

Some of the Coastal Explorer 2009 functions including chart updates and access to satellite maps are via the internet, so we chose a Cradlepoint Wi-Fi access point/router. It has a direct USB port that accepts a Verizon Wireless USB modem. Any PC connected to the access point shares the wireless internet connection. At least in the US, that works pretty well at anchor, dock or in the inter-coastal.

One of the installation issues was getting the Standard Horizon GX-2100 integrated for AIS data. It would not communicate with the Moxa server, or for that matter any of my other electronics to get position data unless I hooked it up to the "PC" port on the Furuno. It turns out that it uses RS232 communications, and while this works with RS422 by luck sometimes, not in our case. {More on that subject here -- ed.} So we added a Startech RS232 to RS422 converter to sit between the GX-2100 and other NMEA equipment. These devices are insensitive to speed, it still sends AIS at high speed and receives position data at low speed with only one interface.

All of these network devices came powered by "110V wall warts". Two of them, the Moxa server, and the Cradlepoint will run on 12V DC. We chose to run them off the wall warts to somewhat isolate them from the ships grounding system. I'm not 100% sure this was the right decision, but I went with it anyway.

One of the primary motivations behind this configuration was to minimize wiring to the laptop on the fly bridge. We chose a ruggedized Dell XFR D630 laptop. While not quite as rugged as the E6400 XFR model that's offered in their current lineup, it was available on Ebay at the right price. However, the "waterproofing" clearly depends on the port access doors being closed. With this setup, the only open port is the power connection. It's notable that the display on this laptop is clearly readable even in direct sunlight. Outside under the canvas, it's more than bright enough for our purposes.

Bob has tested all this pretty thoroughly but other projects prevent him from getting underway for a while. Here's hoping all goes well then, and that he reports back. Thanks, Bob!

Moxa have versions which supports RS232, RS422 and RS485. I have very good experience with the 1-port Moxa NPORT 5150. They have also 4 and 8 ports units supporting all three standards as well as 1, 2 and 4 port WLAN units.

This is an interesting concept but, the equivalent of the Moxa converter is ALREADY BUILT INTO THE FURUNO Navnet DISPLAY!!

In fact, ALL of the the Wall Wart and Moxa Stuff can simply REMOVED FROM THE SYSTEM DIAGRAM ABOVE!

I know this will work if Maxsea Time Zero is substituted instead of the CE program but, Furuno's Built-in Navnet Ethernet port might even work with the Real Com Port Driver as well. It would only take a $50 Furuno Ethernet cable to plug in and try it. Here is the Furuno part number for the cable if Bob wants to try it: 000-159-705. Again all of the RS232/RS422 Issues will vanish and all of the Moxa components should be able to be COMPLETELY REMOVED from the above diagram. It is simply not required because the functionality is already built into the Navnet display. This also true for Navnet vx2 and Navnet 3D as well.

I'll even call Furuno Tech Support and tell them to let Bob borrow a cable to test this functionality if he contacts Furuno and references this post.

Not alot of time to comment at the moment -- off to work this afternoon. But I don't think the Furuno cable would solve the NMEA HS requirement for AIS access, but it might remove the NMEA connection for the data I get off the Furuno box. I also wonder if I could get the CE2009 autopilot sentances to pass through Furuno too.

Your comment is true with Navnet 1 which unfortunately was developed before the AIS Standards were completed. Navnet 1 does not have AIS display or NMEA0183-to-Ethernet Conversion Capabilities. However, Navnet vx2 and Navnet 3D do indeed have these capabilities. We were the first to provide this conversion for our standard and commercial/deep-sea products. We still use it today and this conversion process has been argued against NMEA2000 AIS on this blog. I still don't see NMEA2000 AIS as being very relevent for our products or especially PC Plotting Software customers because of this conversion process.

Simply plug any AIS Class A/Class B or Receiver into the vx2 display and the conversion to UDP over Ethernet for AIS contacts is automatically done with any Navnet vx2 or Navnet 3D MFD. If our FA30 AIS Receiver or our FA50 CLASS B AIS is used, there is an Ethernet port already provided on the box and the data will be there without using an MFD to convert the data. More redundant and more reliable, which is generally true with any Furuno Products.

The CE,or any, Plotter's Autopilot Sentences will pass through the Navnet 1 display if you select "External RMB" in the Plotter Setup Menu. Navnet 1 will automatically use an Externally Received RMB string as its own wpt when the data is received from CE on any Navnet 1 or vx2 Display. Navnet 3 doesn't support this capability because we naturally want to sell Maxsea Time Zero which smokes CE in my very biased opinion anyway. Especially with Maxsea TZ's new real-time POI data, online AIS, panoramic photos, and Workspace concept and other new User Interface features. Ben reported on this new Maxsea feature that will be released this month as discussed here:

Anyway, call our Camas facility if you want to try the cable. I can even let you borrow a Navnet vx2 Display which will plug and play right into your Navnet 1 Display's location if you want to try it with AIS over Ethernet to CE as well. Again, I know this will work with Maxsea Time Zero.

I'll let our Tech Support know you want to try it and I'll answer Ben's questions separately as well.

This supports my whole point (which I've whined about in the past here) where we don't really need n2k - or anything proprietary - as a protocol, because existing payloads delivered over TCP/IP protocol is sufficient!

Thanks for the very complete explanation of the options available. I'd also like to highlight the excellent sales support from the Furuno Florida sales rep we met at the Stuart boat show and later spoke to on the phone about options for the "upgrade" to the electronics on Mar Azul. Finally I had a couple of questions during the install itself, expertly and timely handled by your phone support group in one call.

What it boiled down to for us was cost. I agree completely that Navnet 3D and MaxSea TZ is an awesome package. But that combination with AIS was several times our 2K budget for this project - before I replaced the radar - whick I think is required for display on Navnet 3.

What I wanted was:

1) Dual nav stations, one up one down
2) Better chart depictions than possible on the Gen 1 NavNet
3) AIS display
4) Radar overlay on at both nav stations

Of course it was impossible to accomplish all that for 2K. So I had to make a compromise somewhere.

The most cost effective Furuno solutions that I understood were:

Option A

1) Get the rugged notebook
2) Use the older version of Maxsea that will talk to Navnet 1
3) Add an AIS receiver

Option B

1) Navnet vx2 Display
2) Add an AIS receiver

In round numbers, either option would have been somewhere near 3K. And for discussion purposes, let's say my Navnet 1 display or Radar dies beyond economic repair in 3 years (they are already like 4-5 years old), no clear path to replace the equipment (without starting over) since there is limited compatibility between Navnet 1/vx2 and 3D. (please correct me if this is incorrect...)

But if the price point of the Maxsea version that integrated with our radar been under $500, we would have had a much tougher decision.

The option we choose, gave us everything but radar integration at both places in the 2K budget. We still have radar with the Navnet 1 if we move the display since Mar Azul came "wired" at both stations.

So it was a budgetary compromise. That's not to say what we ended up with is subpar - I've been very impressed with CE 2009 so far.

I appreciate the offer to loan me a cable to try some other configuration options. We will think about using the ethernet integration on the Navnet 1 diaplay. It would potentially free up both NMEA slow tx/rx speed ports on the Moxa server if I can think of something else that might need it.

I'm inclined to leave the design stand because of the level of fault tolerance though. Other than the autopilot itself, any single component in the drawing can fail, and we still have a usable GPS position, chartplotter and full autopilot integration.

I hope this gives you some additional insight on how I ended up with the design shown in this system.

I have a Furuno vx2 System and Furuno Tech Support just told me that all of the above capabilities are possible with Maxsea Time Zero Navigator. Time Zero Navigator is only $450 list price and includes all of the above capabilites except radar on my vx2 display. They said that the Explorer version is the one that goes with Navnet 3D. I can also upgrade to this in the future for my next boat.

I found it on line for about $375 and I'm going to try it on my boat as described above.

Does anybody know if Garmin 5200 series has this capability that Furuno has? I have been eying an RS-422 to ethernet converter for many months but haven't really been able to justify the cost. I know from an inside source that you can hook the Garmin up to a regular ethernet but my source was somewhat vague as to what you could actually do with the data.

I have a laptop set up with Nobeltec and wired ethernet in the boat, so in an emergency it would be an easy matter for me to hook up my backup GPS puck and radar. It would be a lot cooler if I could also get my NMEA data and far cooler if I could do it wirelessly.

Thanks. I like the diagram. I have some of my system but it is not very cool. It might be interesting, however, if Panbo had a place for people to deposit diagrams like this. It is helpful. For example, I have never gotten my Simrad AP22 to recognize NMEA in2 for routing but from this diagram I see that it is possible -- so I know to keep trying.

George, You can generally interconnect all modern networkable multifunction displays with standard Ethernet cables (Lowrance excepted), but you don't get the waterproof plug housing, which varies from brand to brand. And I think they all bridge NMEA 0183 data onto Ethernet to share with other MFDs of the same brand (and often just the same model series).

But the data is generally not accessible to anything else. Maybe Furuno has gone a little further that way than others but what they seem to saying above is that it's mainly meant to work with their own PC software MaxSea. In a comment above I asked for some guidance about how to go from an MFD12 via Ethernet to Coastal Explorer but they haven't advised yet, and it's certainly not in the manual.

Can't help with the Garmin question. But to use 2 nav inputs on the AP22 it worked like this for me:

1) Wire it like the Double NMEA input/output picture in the manual. I did not wire the second "output" on the AP22 back to the chartplotter PC. Maybe someone else will chime in, but I don't think its required.

2) In the Dockside Installation Procedure, confirm port 1 is assigned to GPS1 and then assign port 2 to GPS2. I think, but can't confirm, that GPS1 and 2, Nav1 and 2, LC1 and 2 are all interchangeable. But this choice is used in the next step.

3) In normal use, the User Setup menu is where you select which input to steer by. It's a quick double press on the NAV button to enter this mode. In my config, I set both POS Source and NAV Source to GPS1 or GPS2, depending on which input I want to use.

I spent 5 weeks on the water last year with my original configuration, and never knew about that User Setup menu. Did not really need it either, but that was what I had to search for to figure out how to switch back and forth.

Ben, If it's a UDP connection, I'm not sure CE will support it. Have to ask the Rose Point folks. But generally speaking a "telnet" connection requires TCP. All of my CE interfaces to the Moxa are TCP telnet ones.

But then again it's used a lot. In fact, yesterday I noticed a diagnostic screen on the Simrad NSE that gives UDP transmission statistics and an IP address. Maybe Simrad is doing something similar to Furuno, and hence there's another interface opportunity that could be opened up?

"I'm inclined to leave the design stand because of the level of fault tolerance though. Other than the autopilot itself, any single component in the drawing can fail, and we still have a usable GPS position, chartplotter and full autopilot integration. "

Speaking as someone contemplating the same level of redundancy, and wary of too much unnecessary duplication, this is an important consideration.

I am moving toward a PC-based plotter solution as I don't need a plotter at the outside (deck) helm of my pilothouse cutter sailboat, when just any old GPS with a waypoint/COG will do in most situations. The plotter can be in the pilothouse and the radar display can stand alone.

Personally, I prefer to set the AP to a desired course and NOT to integrate with the plotter as I believe this is an accident waiting to happen and makes the watch lazy. That's just my viewpoint, however, as I consider almost all electronic nav aids subordinate to the Mark 1 Eyeball and the most recent, corrected paper charts.

What is desirable, however, is to have AIS and radar display outputs as optional overlays to the plotter display (in this case a PC that perhaps outputs to a larger display in the saloon for "big picture" route planning). Problems with the GPS plot either in terms of accuracy or "freshness" are immediately apparent when the radar overlay is not matching the plotted coastline, or the AIS shows a ship docked at some pier that didn't make the last plotter update.

So in essence I find the drive for integration of various black-boxes to one display to be undesirable in the same way I don't want to have a can opener on the side of my sextant.

"A "reliable" service is one that notifies the user if delivery fails, while an "unreliable" one does not notify the user if delivery fails. For example, IP provides an unreliable service. Together, TCP and IP provide a reliable service, whereas UDP and IP provide an unreliable one. All these protocols use packets, but UDP packets are generally called datagrams."

Anything on Ethernet is accessable, but you have to figure out how to decode it. If they don't go to great lengths to encrypt the data then it should be fairly easy (although I wouldn't depend on it working from version to version.)

Ideally, Furno and Garmin (et. al) would provide software drivers similar to the drivers sold with the Moxa NPort to implement a virtual NMEA-0183 or NMEA-2000 port. I would happily pay $30-$40 for such a program (Windows NT, please) which is already probably something that they have internally for testing purposes.

It might make a nice way to extract some extra revenue from the product for little up-front cost. $30 for NMEA, $80 for NMEA-2000, $30 for AIS, $300 for Koden-compatible radar output. (Although I wouldn't hold my breath for the latter, it is probably hard.) It wouldn't really cannibilize sales since you would have to have an MFD for it to work.

Also, UDP on a LAN (i.e. not routed) is more reliable than people suspect. In general the local Ethernet card will do its best to ensure that a UDP datagram handed to it is sent. Since all networks now use switches instead of hubs there are no packet collisions. The switch will queue up the packets from all senders and send them out to the receivers.

In fact you could argue that UDP is better than TCP in these cases, as there will be fresher, better, data in one or two seconds (when the TCP stack would send a retry). It's better to send the improved newer depth reading, for instance, than to retry and send the old data. Especially when the receivers give feedback that the data is "old" (e.g. refreshed longer ago than a few seconds).

"Unreliable" is a term of art as the lawyers say. It is an unfortunate name; TCP sockets are arguably more reliable than the CAN-based throttle control in your Toyota...

The Ethernet was designed to allow command and control decisions to be made across the country in the aftermath of a nuclear attack. (Remember when we worried about those?) It is theoretically designed to deal with worst-case scenarios like trying to send a message from New York to California given that Chicago gets wiped out during the transmission. Rest assured that if this happens, your YouTube videos will continue without any noticable hitch.

It is way overdesigned for something as simple as a boat network. It was frustrating to see people speak owlishly about collisions, network bandwidth, and non-guarenteed reception when talking about the virtues of NMEA 2000 vs Ethernet. None of these are even remotely issues with modern ethernet. The thing was designed to work reliably when 2400 baud modems were the hot telecoms device, with 100mbps networks it is almost inconceviable that you will ever even see a packet collision on a boat -- even if you are watching a YouTube video from New York!

A serial Data Router /Buffer / Multiplexer / Converter
MAGICPLEX8 is an intelligent channel multiplexer/serial data router for NMEA-data and a real revolution on the market and is in the moment absolute unique. The first European presentation was at Mets 2009 and the feedback from the visitors where absolutely overwhelming. Magicplex 8 was one of the few high lights of this exhibition.

The technical parameters of the product are top level international leaders. The equipment has 8 channels, which can be operated alternatively as input and output . All interface parameters are, of course, adjustable. The data baud rate can be configured for each channel separately and can have different speed. All ports can be routed to a different port. A Professional Version with IEC 60945 Certification is available for commercial Vessels as well.
Fully flexible NMEA data converter
Ethernet interface (UDP / TCP/IP Client and Server)
8 NMEA 0183 interfaces (inputs and outputs)
NMEA 0183 connections can be set up either as input and as output
speed of all NMEA interfaces are adjustable : from 1.200 Baud to 115.200 Baud
PC interface RS232
CAN-Bus interface
multiplexer and buffer/converter combined in one device
can be fully configured with the supplied PC software
intelligent data management helps to avoid data errors
9-15 V voltage (9-36 V GIC Version)
data logging (such as recording the sailing trip)
data filter dynamically adjustable for high performance
robust casing
superior quality (made in Germany)

Professional Version (GIC) with IEC 60945 Certification available
incl. all inputs and outputs are galvanically isolated

I did some investigation yesterday, and the Nomadics Magicbus8 does seem very well designed for complicated NMEA 0183 situations (though the yacht model costs about 400 euros). There is no U.S. distributor yet, but Nomadics is looking for one.

hello Noel,
thanks for your positive article.
the devices are available. We have one dealer wich also sold to US.
here: http://www.bonito.net/frames/en_mar_index.htm
if you have any questions send me e-mail.
Dealers for US are welcome.